There are known methods for the transfer of energy in pressworking, in which the energy is accumulated and transmitted to the article only once for each working stroke of the pressing machine.
There are also known presses utilizing this method and comprising a flywheel for accumulating the energy of their motor, a clutch, and a crank-, eccentric- or cam-type mechanism with a slider for a single release of the required amount of energy to the article.
For some working operations by the known methods there are used mechanical presses which comprise low-inertia motors with transmission gear, a power cam which is in contact with a roll attached to a quaternary (four-hinge) lever system for proportional force transformation, connected to an elastically deformable member, such as a rod or disk springs, for accumulating the required amount of energy and connected to a working member for a single release of this energy to the article.
There are also hydraulic presses which utilize a hydraulic power unit, a hydraulic accumulator and a hydraulic power cylinder for single release of the required amount of mechanical energy to the worked article of metal, plastics, molding powder, granules, etc.
A general drawback of the known methods for effecting the aforementioned production processes is that when greater energy amplitude is necessary for pressworking a particular article, it is necessary to use a more expensive and more powerful press of heavier weight. In the case of presses with a flywheel or with elastic deformable members it is necessary to use a more expensive and more powerful machine of heavier weight also because of the shortness of the power stroke.
Another drawback of the aforementioned flywheel machines is that they operate with impacts and the article cannot be maintained compressed by them in order to subject it to additional treatment, this requiring the use of the more expensive hydraulic presses.
It is possible to utilize from the flywheel of such presses in one working stroke of the slider only a small portion of the total large quantity of kinetic energy accumulated in the flywheel and, moreover, the power stroke, i.e. this portion of their total stroke at which they can release their nominal force, is comparatively short with abrupt transitions.
The power strokes of mechanical presses are comparatively short, their auxiliary stroke is even shorter, and the force is applied to the workpiece according to a decreasing force function, proportional to the reduction of the stress in discharge of the energy elastic deformable member. All this narrows the sphere of application of these presses.
A drawback of the hydraulic presses lies in that they are of heavier weight, are more expensive, more complex and less reliable, slower and with a lower productivity than the mechanical presses, they require a larger floor area, and have a lower energy efficiency because of the repeated energy transformation and the losses for regulation. The simultaneous control of released energies, displacements and velocities is practically not realizable.